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<FONT color="green">001</FONT>    /*<a name="line.1"></a>
<FONT color="green">002</FONT>     * Licensed to the Apache Software Foundation (ASF) under one or more<a name="line.2"></a>
<FONT color="green">003</FONT>     * contributor license agreements.  See the NOTICE file distributed with<a name="line.3"></a>
<FONT color="green">004</FONT>     * this work for additional information regarding copyright ownership.<a name="line.4"></a>
<FONT color="green">005</FONT>     * The ASF licenses this file to You under the Apache License, Version 2.0<a name="line.5"></a>
<FONT color="green">006</FONT>     * (the "License"); you may not use this file except in compliance with<a name="line.6"></a>
<FONT color="green">007</FONT>     * the License.  You may obtain a copy of the License at<a name="line.7"></a>
<FONT color="green">008</FONT>     *<a name="line.8"></a>
<FONT color="green">009</FONT>     *      http://www.apache.org/licenses/LICENSE-2.0<a name="line.9"></a>
<FONT color="green">010</FONT>     *<a name="line.10"></a>
<FONT color="green">011</FONT>     * Unless required by applicable law or agreed to in writing, software<a name="line.11"></a>
<FONT color="green">012</FONT>     * distributed under the License is distributed on an "AS IS" BASIS,<a name="line.12"></a>
<FONT color="green">013</FONT>     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<a name="line.13"></a>
<FONT color="green">014</FONT>     * See the License for the specific language governing permissions and<a name="line.14"></a>
<FONT color="green">015</FONT>     * limitations under the License.<a name="line.15"></a>
<FONT color="green">016</FONT>     */<a name="line.16"></a>
<FONT color="green">017</FONT>    <a name="line.17"></a>
<FONT color="green">018</FONT>    package org.apache.commons.math3.analysis.function;<a name="line.18"></a>
<FONT color="green">019</FONT>    <a name="line.19"></a>
<FONT color="green">020</FONT>    import java.util.Arrays;<a name="line.20"></a>
<FONT color="green">021</FONT>    import org.apache.commons.math3.analysis.UnivariateFunction;<a name="line.21"></a>
<FONT color="green">022</FONT>    import org.apache.commons.math3.exception.DimensionMismatchException;<a name="line.22"></a>
<FONT color="green">023</FONT>    import org.apache.commons.math3.exception.NullArgumentException;<a name="line.23"></a>
<FONT color="green">024</FONT>    import org.apache.commons.math3.exception.NoDataException;<a name="line.24"></a>
<FONT color="green">025</FONT>    import org.apache.commons.math3.util.MathArrays;<a name="line.25"></a>
<FONT color="green">026</FONT>    <a name="line.26"></a>
<FONT color="green">027</FONT>    /**<a name="line.27"></a>
<FONT color="green">028</FONT>     * &lt;a href="http://en.wikipedia.org/wiki/Step_function"&gt;<a name="line.28"></a>
<FONT color="green">029</FONT>     *  Step function&lt;/a&gt;.<a name="line.29"></a>
<FONT color="green">030</FONT>     *<a name="line.30"></a>
<FONT color="green">031</FONT>     * @since 3.0<a name="line.31"></a>
<FONT color="green">032</FONT>     * @version $Id: StepFunction.java 1379218 2012-08-30 23:18:57Z erans $<a name="line.32"></a>
<FONT color="green">033</FONT>     */<a name="line.33"></a>
<FONT color="green">034</FONT>    public class StepFunction implements UnivariateFunction {<a name="line.34"></a>
<FONT color="green">035</FONT>        /** Abscissae. */<a name="line.35"></a>
<FONT color="green">036</FONT>        private final double[] abscissa;<a name="line.36"></a>
<FONT color="green">037</FONT>        /** Ordinates. */<a name="line.37"></a>
<FONT color="green">038</FONT>        private final double[] ordinate;<a name="line.38"></a>
<FONT color="green">039</FONT>    <a name="line.39"></a>
<FONT color="green">040</FONT>        /**<a name="line.40"></a>
<FONT color="green">041</FONT>         * Builds a step function from a list of arguments and the corresponding<a name="line.41"></a>
<FONT color="green">042</FONT>         * values. Specifically, returns the function h(x) defined by &lt;pre&gt;&lt;code&gt;<a name="line.42"></a>
<FONT color="green">043</FONT>         * h(x) = y[0] for all x &lt; x[1]<a name="line.43"></a>
<FONT color="green">044</FONT>         *        y[1] for x[1] &lt;= x &lt; x[2]<a name="line.44"></a>
<FONT color="green">045</FONT>         *        ...<a name="line.45"></a>
<FONT color="green">046</FONT>         *        y[y.length - 1] for x &gt;= x[x.length - 1]<a name="line.46"></a>
<FONT color="green">047</FONT>         * &lt;/code&gt;&lt;/pre&gt;<a name="line.47"></a>
<FONT color="green">048</FONT>         * The value of {@code x[0]} is ignored, but it must be strictly less than<a name="line.48"></a>
<FONT color="green">049</FONT>         * {@code x[1]}.<a name="line.49"></a>
<FONT color="green">050</FONT>         *<a name="line.50"></a>
<FONT color="green">051</FONT>         * @param x Domain values where the function changes value.<a name="line.51"></a>
<FONT color="green">052</FONT>         * @param y Values of the function.<a name="line.52"></a>
<FONT color="green">053</FONT>         * @throws org.apache.commons.math3.exception.NonMonotonicSequenceException<a name="line.53"></a>
<FONT color="green">054</FONT>         * if the {@code x} array is not sorted in strictly increasing order.<a name="line.54"></a>
<FONT color="green">055</FONT>         * @throws NullArgumentException if {@code x} or {@code y} are {@code null}.<a name="line.55"></a>
<FONT color="green">056</FONT>         * @throws NoDataException if {@code x} or {@code y} are zero-length.<a name="line.56"></a>
<FONT color="green">057</FONT>         * @throws DimensionMismatchException if {@code x} and {@code y} do not<a name="line.57"></a>
<FONT color="green">058</FONT>         * have the same length.<a name="line.58"></a>
<FONT color="green">059</FONT>         */<a name="line.59"></a>
<FONT color="green">060</FONT>        public StepFunction(double[] x,<a name="line.60"></a>
<FONT color="green">061</FONT>                            double[] y)<a name="line.61"></a>
<FONT color="green">062</FONT>            throws NullArgumentException,<a name="line.62"></a>
<FONT color="green">063</FONT>                   NoDataException,<a name="line.63"></a>
<FONT color="green">064</FONT>                   DimensionMismatchException {<a name="line.64"></a>
<FONT color="green">065</FONT>            if (x == null ||<a name="line.65"></a>
<FONT color="green">066</FONT>                y == null) {<a name="line.66"></a>
<FONT color="green">067</FONT>                throw new NullArgumentException();<a name="line.67"></a>
<FONT color="green">068</FONT>            }<a name="line.68"></a>
<FONT color="green">069</FONT>            if (x.length == 0 ||<a name="line.69"></a>
<FONT color="green">070</FONT>                y.length == 0) {<a name="line.70"></a>
<FONT color="green">071</FONT>                throw new NoDataException();<a name="line.71"></a>
<FONT color="green">072</FONT>            }<a name="line.72"></a>
<FONT color="green">073</FONT>            if (y.length != x.length) {<a name="line.73"></a>
<FONT color="green">074</FONT>                throw new DimensionMismatchException(y.length, x.length);<a name="line.74"></a>
<FONT color="green">075</FONT>            }<a name="line.75"></a>
<FONT color="green">076</FONT>            MathArrays.checkOrder(x);<a name="line.76"></a>
<FONT color="green">077</FONT>    <a name="line.77"></a>
<FONT color="green">078</FONT>            abscissa = MathArrays.copyOf(x);<a name="line.78"></a>
<FONT color="green">079</FONT>            ordinate = MathArrays.copyOf(y);<a name="line.79"></a>
<FONT color="green">080</FONT>        }<a name="line.80"></a>
<FONT color="green">081</FONT>    <a name="line.81"></a>
<FONT color="green">082</FONT>        /** {@inheritDoc} */<a name="line.82"></a>
<FONT color="green">083</FONT>        public double value(double x) {<a name="line.83"></a>
<FONT color="green">084</FONT>            int index = Arrays.binarySearch(abscissa, x);<a name="line.84"></a>
<FONT color="green">085</FONT>            double fx = 0;<a name="line.85"></a>
<FONT color="green">086</FONT>    <a name="line.86"></a>
<FONT color="green">087</FONT>            if (index &lt; -1) {<a name="line.87"></a>
<FONT color="green">088</FONT>                // "x" is between "abscissa[-index-2]" and "abscissa[-index-1]".<a name="line.88"></a>
<FONT color="green">089</FONT>                fx = ordinate[-index-2];<a name="line.89"></a>
<FONT color="green">090</FONT>            } else if (index &gt;= 0) {<a name="line.90"></a>
<FONT color="green">091</FONT>                // "x" is exactly "abscissa[index]".<a name="line.91"></a>
<FONT color="green">092</FONT>                fx = ordinate[index];<a name="line.92"></a>
<FONT color="green">093</FONT>            } else {<a name="line.93"></a>
<FONT color="green">094</FONT>                // Otherwise, "x" is smaller than the first value in "abscissa"<a name="line.94"></a>
<FONT color="green">095</FONT>                // (hence the returned value should be "ordinate[0]").<a name="line.95"></a>
<FONT color="green">096</FONT>                fx = ordinate[0];<a name="line.96"></a>
<FONT color="green">097</FONT>            }<a name="line.97"></a>
<FONT color="green">098</FONT>    <a name="line.98"></a>
<FONT color="green">099</FONT>            return fx;<a name="line.99"></a>
<FONT color="green">100</FONT>        }<a name="line.100"></a>
<FONT color="green">101</FONT>    }<a name="line.101"></a>




























































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